US5081617A - Optical system for simultaneous reading of multiple data tracks - Google Patents

Optical system for simultaneous reading of multiple data tracks Download PDF

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Publication number
US5081617A
US5081617A US07586837 US58683790A US5081617A US 5081617 A US5081617 A US 5081617A US 07586837 US07586837 US 07586837 US 58683790 A US58683790 A US 58683790A US 5081617 A US5081617 A US 5081617A
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Prior art keywords
data tracks
line
track
tracks
detectors
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Expired - Fee Related
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US07586837
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Daniel Gelbart
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Creo Inc
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Creo Inc
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    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
    • G11B7/1372Lenses
    • G11B7/1374Objective lenses
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/13Optical detectors therefor
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/14Heads, e.g. forming of the optical beam spot or modulation of the optical beam specially adapted to record on, or to reproduce from, more than one track simultaneously

Abstract

An optical system for reading and tracking multiple tracks of optically recorded data consists of a combination of spherical and cylindrical lenses shaping the emission of a laser diode into a narrow line on the surface of the recorded material. This line is subsequently imaged on a detector array containing multiple detectors for each data track being read. Digital signal processing identifies the tracks and follows them by selecting the proper detectors in the detector array. Track-to-track interference is minimized by selecting the numerical aperture of the final lens to have the nulls of the Airy pattern at double the track spacing.

Description

BACKGROUND OF THE INVENTION

The present invention relates to optical reading of multiple data tracks simultaneously. This is of particular interest in optical data storage and in optical inspection systems. Previous multi-track systems required breaking up the laser beam into multiple read beams and mechanically tracking the recorded data. A typical example for such a system is U.S. Pat. No. 4,283,777. Other systems used broad illumination of the read area and electronic tracking to read a single track such as U.S. Pat. No. 4,337,534. Using broad illumination increases cross-talk between tracks and give poor results when used with laser light due to laser speckle.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a readout system compatible with electronic tracking while maintaining the high signal-to-noise and low crosstalk of single spot tracking. A further object is to provide a wide tracking range and a large readout signal by using a laser as a light source without losing performance due to speckle caused by the coherence of the laser.

These objects, as well as others which will become apparent from the text which follows, are achieved by shaping the beam of a laser into a line and imaging that line onto the tracks being read, the line being perpendicular to the direction of the tracks. The line imaged onto the tracks is re-imaged onto a detector array followed by an electronic tracking circuit. An example of such a electronic tracking circuit can be found in U.S. Pat. No. 3,780,266 and will not be further detailed since it is well known in the art. The line imaged onto the tracks is scanned in the direction of the tracks by any of the well known laser beam scanning methods. These methods involve moving the material carrying the data tracks in the direction of the tracks or moving the image of the line on the stationary material. No further details of the scanning will be given since it does not form part of this invention.

The read signal can be maximized and the track-to-track cross talk minimized by selecting the optical parameters as follows: The width of the illuminating line in the direction of the tracks should be about the size of the smallest mark being read. The numerical aperture and the truncation function of the final lens in the system (i.e., the lens looking at the recorded tracks) should be selected that the nulls of the Airy pattern occur at double the track spacing. Under these conditions the track-to-track cross talk is minimized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of the present invention.

FIG. 2 is a schematic cross section of the Airy spot of the final lens relative to the tracks being read, showing the conditions for minimal cross-talk.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, the light emitted by laser diode 1 is collected by lens 2 and shaped by lens 3 into a narrow line 4. The orientation of laser diode 1 is such that the light is polarized parallel to line 4 and thus reflected by the hypotenuse of polarizing beam splitter 5. A quarter-wave plate 10 causes the light entering imaging lens 6 to be circularly polarized. Those versed in the art will recognize this arrangement as the well known optical isolator. Imaging lens 6 forms an image 7 of line 4 on the surface of recorded material 8 carrying a plurality of recorded tracks 9. The light reflected from line 7 is modulated by the data of tracks 9 and is re-imaged onto a detector array 12 using imaging lens 6 and a second imaging lens 11. Since the returned light from material 8 passes through waveplate 10 it will convert from circular polarization to linear polarization orthogonal to line 4 and will not be reflected by polarizing beam splitter 5. Diode array 12 has multiple detectors for each one of tracks 9 as well as extra detectors at ends to allow the image of tracks to wander on detector array without losing data. An electronic tracking unit 13 tracks the image and generates the output data. The operation of the electronic tracking is fully explained in U.S. Pat. No. 3,780,266 and no further data will be given here. The detector array 12 and electronic tracking 13 can be integrated into a single monolithic integrated circuit. In order to minimize track-to-track cross talk and maximize the readout signal the numerical aperture of lens 6 has to be chosen relative to the wavelength λ of the laser diode 1 and the spacing of the tracks to be read, shown as "p" in FIG. 1 and 2. Referring now to FIG. 2, graph 14 shows a cross section of a single spot formed by lens 6 on material 8. The cross section is the well known Airy pattern and it is a function of three parameters: The wavelength λ, the numerical aperture of lens 6 (N.A.) and the truncation function of the light by the aperture of lens 6. Depending on the degree of truncation selected, the Airy pattern will have a null, also known as a dark ring, at a radius from 0.6 λ/N.A. to about 0.8 λ/N.A. When the track pitch "p" matches these nulls, the cross-talk between the tracks is minimized. This can be explained by viewing the line 7 as a summation of many points but only points which are a distance "p" apart, are sampled by the tracking circuit 13. For points a distance "p" apart along line 7, the Airy pattern of one point does not contribute to the sampling point of the Airy pattern of the next point, if the second point is located at a null of the first Airy pattern.

In order to scan material 8, any one of the well known scanning methods can be used along the track direction. If the spacing of the recorded marks along the track directions is also "p", same benefits of minimizing cross talk along the track (also known as inter-symbol interference) will occur. In general, the cross-talk between marks in the track direction can always be reduced by making the line narrower (using a higher N.A. for lens 6) but the cross-talk between tracks will only be minimized at a specific N.A. which satisfies p=0.6 λ/N.A. to 0.8 λ/N.A. By the way of example values will be given for a system reading track on a 1.5 micron pitch at a wavelength of 0.83 microns. Since "p"=0.6 λ/N.A. to 0.8 λ/N.A., N.A. should be from 0.33 to 0.44. A lens 6 with N.A.=0.4 would be a good choice. The selection of the other lenses is not critical. Lens 11 is chosen to match the image of the tracks to the detector pitch. By the way of example, laser diode 1 is model LT015MD made by Sharp (Japan), lens 2 and lens 6 are aspheric plastic lenses of f=4.5 N.A.=0.4, lens 3 is a cylindrical lens of f=25 mm, optical isolator 5 is a readily available commercial component. Detector array 12 and tracking electronics 13 are a monolithic integrated circuit and four detectors are used for each track. If detector pitch is, by the way of example, 20 microns, lens 11 has to magnify image of tracks formed by lens 6 until the magnified track pitch as projected onto detector array 12 equals 80 microns. This is readily accomplished by selecting the correct focal length and spacing for lens 11.

Claims (3)

What is claimed is:
1. An optical system for the simultaneous reading of a plurality of data tracks with minimal optical cross-talk between tracks comprising of a laser; at least one lens collecting light from said laser and shaping it into a line; an imaging lens imaging said line onto said data tracks, image of said line being perpendicular to said data tracks, said imaging lens minimizes the said optical cross-talk between said data tracks while capturing the light reflected back from said data tracks, said minimizing of cross-talk is achieved by choosing a numerical aperture for said imaging lens generating Airy pattern nulls at approximately double the spacing of said data tracks; and array of photo-detectors and means of projecting said reflected light onto said photo-detectors, the number of said photo-detectors being at least twice the number of data tracks being read in order not to require the light reflected from any of said data tracks to line up with any particular one of said photo-detectors.
2. An optical system for the simultaneous reading of a plurality of data tracks as recited in claim 1 wherein the numerical aperture of said imaging lens is selected to be between 60% to 100% of the wavelength of said laser divided by the center-to-center spacing of said data tracks in order to minimize the cross-talk between track while at the same time forming a diffraction limited line in the track direction.
3. An optical system for the simultaneous reading of a plurality of data tracks as recited in claim 1, wherein said laser is a diode laser, said line is formed by using a spherical lens followed by a cylindrical lens, and there are four of said photo-detectors detecting per data track being read.
US07586837 1990-09-24 1990-09-24 Optical system for simultaneous reading of multiple data tracks Expired - Fee Related US5081617A (en)

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Cited By (51)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0542402A1 (en) * 1991-11-12 1993-05-19 Pioneer Electronic Corporation Pickup device
EP0545526A1 (en) * 1991-12-03 1993-06-09 Pioneer Electronic Corporation Optical pickup apparatus
US5237556A (en) * 1991-12-24 1993-08-17 Samsung Electronics Co., Ltd. Wide beam detector system for optical memories
US5247510A (en) * 1990-06-29 1993-09-21 Digital Equipment Corporation Increasing storage density of optical data media by detecting a selected portion of a light spot image corresponding to a single domain
EP0568010A1 (en) * 1992-04-28 1993-11-03 Olympus Optical Co., Ltd. Method and apparatus for reading optical data
US5321683A (en) * 1992-12-28 1994-06-14 Eastman Kodak Company Digital optical tape read system
US5440419A (en) * 1992-04-24 1995-08-08 E-Systems, Inc. Read-write head for an optical tape recorder
US5465243A (en) * 1992-04-24 1995-11-07 E-Systems, Inc. Optical recorder and reader of data on light sensitive media
US5471454A (en) * 1992-05-27 1995-11-28 Olympus Optical Co., Ltd. Optical head having semiconductor laser
US5524105A (en) * 1992-12-29 1996-06-04 Eastman Kodak Company Helical optical tape read/write system using at least one laser array
US5535189A (en) * 1992-04-10 1996-07-09 Alon; Amir Optical information system with a broad non-coherent irradiating beam coupled with optical fiber from a laser source
US5561654A (en) * 1995-06-07 1996-10-01 E-Systems, Inc. Compact write system for optical tape recording
US5563867A (en) * 1994-06-30 1996-10-08 Discovision Associates Optical tape duplicator
US5566159A (en) * 1993-10-04 1996-10-15 Zen Research N.V. Optical disk reader
WO1996041335A2 (en) * 1995-06-07 1996-12-19 E-Systems, Inc. Compact read/tracking system for optical tape recording
US5592444A (en) * 1993-06-14 1997-01-07 Zen Research N.V. Method of writing data simultaneously on a plurality of tracks of an optical disk, and apparatus therefor
US5627805A (en) * 1995-11-15 1997-05-06 Zen Research N.V. Methods and apparatus for high speed optical storage device
US5652746A (en) * 1995-11-15 1997-07-29 Zen Research N.V. Electronic track detection methods for apparatus for simultaneously reading multiple adjacent tracks of an optical disk
US5701283A (en) * 1995-11-15 1997-12-23 Zen Research N.V. Method and apparatus for high speed optical storage device
US5708634A (en) * 1995-09-20 1998-01-13 Zen Research N.V. Focussing system and methods for multi-track optical disk apparatus
WO1998001858A1 (en) * 1996-07-08 1998-01-15 Zen Research N.V. Apparatus and methods for providing non-coherent laser illumination for multi-track reading apparatus
US5793715A (en) * 1995-11-15 1998-08-11 Zen Research N.V. Methods and apparatus for reducing the access time of an optical drive
US5793549A (en) * 1995-11-15 1998-08-11 Zen Research N.V. Methods and apparatus for synchronizing read out of data from multiple tracks of an optical storage device
US5802025A (en) * 1995-11-15 1998-09-01 Zen Research N.V. Track detection methods and apparatus for simultaneous monitoring of multiple adjacent tracks of an optical disk
US5802034A (en) * 1996-12-09 1998-09-01 Gelbart; Daniel Multi-track optical read/write head
US5907526A (en) * 1995-11-15 1999-05-25 Zen Research N.V. Methods and apparatus for simultaneously reading multiple tracks of an optical storage medium
US5917797A (en) * 1997-08-15 1999-06-29 Zen Research Nv Multi-beam optical pickup assembly and methods using a compact two-dimensional arrangement of beams
US6087069A (en) * 1999-04-16 2000-07-11 Presstek, Inc. Lithographic imaging and cleaning of printing members having boron ceramic layers
US6137763A (en) * 1998-09-24 2000-10-24 Zen Research N.V. Method and apparatus for buffering data in a multi-beam optical disk reader
US6222577B1 (en) 1999-01-26 2001-04-24 Presstek, Inc. Multiple-beam, diode-pumped imaging system
US6381210B1 (en) 1995-11-15 2002-04-30 Zen Research (Ireland) Ltd. Methods and apparatus for concurrently processing data from multiple tracks of an optical storage medium
US6396042B1 (en) 1999-10-19 2002-05-28 Raytheon Company Digital laser image recorder including delay lines
US6404708B1 (en) 1998-09-30 2002-06-11 Howard Hong-Dough Lee Optical data-storage apparatus employing optical media with three-dimensional data pattern
US20030038943A1 (en) * 2001-08-21 2003-02-27 Kais Almarzouk Method and apparatus for measuring wavelength jitter of light signal
US20030076760A1 (en) * 2001-10-23 2003-04-24 Koby Finkelstein Methods and apparatus for cross-talk and jitter reduction in multi-beam optical disks
US6712480B1 (en) 2002-09-27 2004-03-30 Silicon Light Machines Controlled curvature of stressed micro-structures
US6728023B1 (en) 2002-05-28 2004-04-27 Silicon Light Machines Optical device arrays with optimized image resolution
US6747781B2 (en) 2001-06-25 2004-06-08 Silicon Light Machines, Inc. Method, apparatus, and diffuser for reducing laser speckle
US6764875B2 (en) 1998-07-29 2004-07-20 Silicon Light Machines Method of and apparatus for sealing an hermetic lid to a semiconductor die
US6767751B2 (en) 2002-05-28 2004-07-27 Silicon Light Machines, Inc. Integrated driver process flow
US6782205B2 (en) 2001-06-25 2004-08-24 Silicon Light Machines Method and apparatus for dynamic equalization in wavelength division multiplexing
US6801354B1 (en) 2002-08-20 2004-10-05 Silicon Light Machines, Inc. 2-D diffraction grating for substantially eliminating polarization dependent losses
US6800238B1 (en) 2002-01-15 2004-10-05 Silicon Light Machines, Inc. Method for domain patterning in low coercive field ferroelectrics
US6806997B1 (en) 2003-02-28 2004-10-19 Silicon Light Machines, Inc. Patterned diffractive light modulator ribbon for PDL reduction
US6813059B2 (en) 2002-06-28 2004-11-02 Silicon Light Machines, Inc. Reduced formation of asperities in contact micro-structures
US6822797B1 (en) 2002-05-31 2004-11-23 Silicon Light Machines, Inc. Light modulator structure for producing high-contrast operation using zero-order light
US6829258B1 (en) 2002-06-26 2004-12-07 Silicon Light Machines, Inc. Rapidly tunable external cavity laser
US6829077B1 (en) 2003-02-28 2004-12-07 Silicon Light Machines, Inc. Diffractive light modulator with dynamically rotatable diffraction plane
US6829092B2 (en) 2001-08-15 2004-12-07 Silicon Light Machines, Inc. Blazed grating light valve
US6999484B2 (en) 2003-03-18 2006-02-14 Eastman Kodak Company Parallel access data storage system using a combination of VCSEL arrays and an integrated solid immersion lens array
US20080279086A1 (en) * 2004-06-03 2008-11-13 Koninklijke Philips Electronics, N.V. Record Carrier Comprising a Rom Mark and a Playback Device For Retrieving the Rom Mark

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Cited By (63)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5247510A (en) * 1990-06-29 1993-09-21 Digital Equipment Corporation Increasing storage density of optical data media by detecting a selected portion of a light spot image corresponding to a single domain
EP0542402A1 (en) * 1991-11-12 1993-05-19 Pioneer Electronic Corporation Pickup device
US5283778A (en) * 1991-11-12 1994-02-01 Pioneer Electronic Corporation Pickup device
US5355361A (en) * 1991-12-03 1994-10-11 Pioneer Electronic Corporation Optical pickup apparatus for reproducing signals recorded on an optical disk
EP0545526A1 (en) * 1991-12-03 1993-06-09 Pioneer Electronic Corporation Optical pickup apparatus
US5237556A (en) * 1991-12-24 1993-08-17 Samsung Electronics Co., Ltd. Wide beam detector system for optical memories
US5537385A (en) * 1992-04-10 1996-07-16 Alon; Amir Reading multiple tracks data with a microscope scanner and a two mirror light beam focus unit
US5535189A (en) * 1992-04-10 1996-07-09 Alon; Amir Optical information system with a broad non-coherent irradiating beam coupled with optical fiber from a laser source
US5574712A (en) * 1992-04-10 1996-11-12 Zen Research N.V. Detector matrix for acquiring track data from multiple tracks
US5598393A (en) * 1992-04-10 1997-01-28 Zen Research N.V. Method and apparatus for reading data
US5465243A (en) * 1992-04-24 1995-11-07 E-Systems, Inc. Optical recorder and reader of data on light sensitive media
US5440419A (en) * 1992-04-24 1995-08-08 E-Systems, Inc. Read-write head for an optical tape recorder
EP0568010A1 (en) * 1992-04-28 1993-11-03 Olympus Optical Co., Ltd. Method and apparatus for reading optical data
US5471454A (en) * 1992-05-27 1995-11-28 Olympus Optical Co., Ltd. Optical head having semiconductor laser
US5321683A (en) * 1992-12-28 1994-06-14 Eastman Kodak Company Digital optical tape read system
US5524105A (en) * 1992-12-29 1996-06-04 Eastman Kodak Company Helical optical tape read/write system using at least one laser array
US5592444A (en) * 1993-06-14 1997-01-07 Zen Research N.V. Method of writing data simultaneously on a plurality of tracks of an optical disk, and apparatus therefor
US5566159A (en) * 1993-10-04 1996-10-15 Zen Research N.V. Optical disk reader
US5563867A (en) * 1994-06-30 1996-10-08 Discovision Associates Optical tape duplicator
WO1996041335A2 (en) * 1995-06-07 1996-12-19 E-Systems, Inc. Compact read/tracking system for optical tape recording
US5561654A (en) * 1995-06-07 1996-10-01 E-Systems, Inc. Compact write system for optical tape recording
WO1996041335A3 (en) * 1995-06-07 1997-02-06 E Systems Inc Compact read/tracking system for optical tape recording
US5708634A (en) * 1995-09-20 1998-01-13 Zen Research N.V. Focussing system and methods for multi-track optical disk apparatus
US5774432A (en) * 1995-09-20 1998-06-30 Zen Research N.V. Focussing system and methods for multi- track optical disk apparatus
US6111831A (en) * 1995-11-15 2000-08-29 Zen Research N. V. Methods and apparatus for simultaneously reading multiple tracks of an optical storage medium
US5701283A (en) * 1995-11-15 1997-12-23 Zen Research N.V. Method and apparatus for high speed optical storage device
US6381210B1 (en) 1995-11-15 2002-04-30 Zen Research (Ireland) Ltd. Methods and apparatus for concurrently processing data from multiple tracks of an optical storage medium
US5652746A (en) * 1995-11-15 1997-07-29 Zen Research N.V. Electronic track detection methods for apparatus for simultaneously reading multiple adjacent tracks of an optical disk
US5793715A (en) * 1995-11-15 1998-08-11 Zen Research N.V. Methods and apparatus for reducing the access time of an optical drive
US5793549A (en) * 1995-11-15 1998-08-11 Zen Research N.V. Methods and apparatus for synchronizing read out of data from multiple tracks of an optical storage device
US5802025A (en) * 1995-11-15 1998-09-01 Zen Research N.V. Track detection methods and apparatus for simultaneous monitoring of multiple adjacent tracks of an optical disk
US5627805A (en) * 1995-11-15 1997-05-06 Zen Research N.V. Methods and apparatus for high speed optical storage device
US5907526A (en) * 1995-11-15 1999-05-25 Zen Research N.V. Methods and apparatus for simultaneously reading multiple tracks of an optical storage medium
US6028827A (en) * 1995-11-15 2000-02-22 Zen Research N.V. Methods and apparatus for synchronizing read out of data from multiple tracks of an optical storage device
WO1998001858A1 (en) * 1996-07-08 1998-01-15 Zen Research N.V. Apparatus and methods for providing non-coherent laser illumination for multi-track reading apparatus
US5802034A (en) * 1996-12-09 1998-09-01 Gelbart; Daniel Multi-track optical read/write head
US5917797A (en) * 1997-08-15 1999-06-29 Zen Research Nv Multi-beam optical pickup assembly and methods using a compact two-dimensional arrangement of beams
US6764875B2 (en) 1998-07-29 2004-07-20 Silicon Light Machines Method of and apparatus for sealing an hermetic lid to a semiconductor die
US6137763A (en) * 1998-09-24 2000-10-24 Zen Research N.V. Method and apparatus for buffering data in a multi-beam optical disk reader
US6404708B1 (en) 1998-09-30 2002-06-11 Howard Hong-Dough Lee Optical data-storage apparatus employing optical media with three-dimensional data pattern
US6222577B1 (en) 1999-01-26 2001-04-24 Presstek, Inc. Multiple-beam, diode-pumped imaging system
US6087069A (en) * 1999-04-16 2000-07-11 Presstek, Inc. Lithographic imaging and cleaning of printing members having boron ceramic layers
US6855923B2 (en) 1999-10-19 2005-02-15 Raytheon Company Scanning a beam of light in a digital image recorder
US6396042B1 (en) 1999-10-19 2002-05-28 Raytheon Company Digital laser image recorder including delay lines
US6747781B2 (en) 2001-06-25 2004-06-08 Silicon Light Machines, Inc. Method, apparatus, and diffuser for reducing laser speckle
US6782205B2 (en) 2001-06-25 2004-08-24 Silicon Light Machines Method and apparatus for dynamic equalization in wavelength division multiplexing
US6829092B2 (en) 2001-08-15 2004-12-07 Silicon Light Machines, Inc. Blazed grating light valve
US20030038943A1 (en) * 2001-08-21 2003-02-27 Kais Almarzouk Method and apparatus for measuring wavelength jitter of light signal
US6940805B2 (en) 2001-10-23 2005-09-06 Dragsholm Wireless Holdings Llc Methods and apparatus for cross-talk and jitter reduction in multi-beam optical disks
US20030076760A1 (en) * 2001-10-23 2003-04-24 Koby Finkelstein Methods and apparatus for cross-talk and jitter reduction in multi-beam optical disks
US6800238B1 (en) 2002-01-15 2004-10-05 Silicon Light Machines, Inc. Method for domain patterning in low coercive field ferroelectrics
US6728023B1 (en) 2002-05-28 2004-04-27 Silicon Light Machines Optical device arrays with optimized image resolution
US6767751B2 (en) 2002-05-28 2004-07-27 Silicon Light Machines, Inc. Integrated driver process flow
US6822797B1 (en) 2002-05-31 2004-11-23 Silicon Light Machines, Inc. Light modulator structure for producing high-contrast operation using zero-order light
US6829258B1 (en) 2002-06-26 2004-12-07 Silicon Light Machines, Inc. Rapidly tunable external cavity laser
US6813059B2 (en) 2002-06-28 2004-11-02 Silicon Light Machines, Inc. Reduced formation of asperities in contact micro-structures
US6801354B1 (en) 2002-08-20 2004-10-05 Silicon Light Machines, Inc. 2-D diffraction grating for substantially eliminating polarization dependent losses
US6712480B1 (en) 2002-09-27 2004-03-30 Silicon Light Machines Controlled curvature of stressed micro-structures
US6806997B1 (en) 2003-02-28 2004-10-19 Silicon Light Machines, Inc. Patterned diffractive light modulator ribbon for PDL reduction
US6829077B1 (en) 2003-02-28 2004-12-07 Silicon Light Machines, Inc. Diffractive light modulator with dynamically rotatable diffraction plane
US6999484B2 (en) 2003-03-18 2006-02-14 Eastman Kodak Company Parallel access data storage system using a combination of VCSEL arrays and an integrated solid immersion lens array
US7916617B2 (en) * 2004-06-03 2011-03-29 Koninklijke Philips Electronics N.V. Recognizable patterns in adjacent tracks of ROM record carriers for simultaneous scanning for copy protection
US20080279086A1 (en) * 2004-06-03 2008-11-13 Koninklijke Philips Electronics, N.V. Record Carrier Comprising a Rom Mark and a Playback Device For Retrieving the Rom Mark

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